Many water soluble polymers (cellulose, cellulose derivatives, gums, and the like) are typically sold in solid, dry, form, and hence powder handling and processing properties are extremely important. For example, a low dust content is desirable. Also, the ability of the dry powder to be poured from a container or receptacle is described as flowability. Flowability is affected by particle shape and size distribution, and resulting bulk density. Bulk density is the mass of powdered solid material per unit of volume occupied. Acceptable flowability generally depends upon relatively high bulk density and relatively low angle of repose. The angle of repose is the maximum angle between the slope of a conical discharged pile of powder and the surface it rests upon, a lower angle representing a more widely spread pile.
As part of using the water soluble polymer in its various applications, the water soluble polymer must be dissolved. Dissolution is frequently described as a process with two overlapping phenomena, dispersion and hydration. Dispersion refers to spreading of particles or groups of polymer chains throughout the solution. Hydration refers to loosening of the polymer chains and expansion of their hydrodynamic volume (and corresponding viscosity buildup). If dispersion is poor, or if hydration outpaces dispersion, hydrated polymer can swell and isolate relatively dry, non-hydrated polymer from the solution, forming lumps. Desirable dispersion and hydration are normally characterized by little to no lump formation and a rapid viscosity build up over time, respectively.
Accordingly, there is a need in the industry to reduce the foregoing problems (dust, variable flow, inconsistent dispersion, or undesirable rate of hydration) in order to simplify formulation of products incorporating water soluble polymers.